Optofluidic lithography system, method of manufacturing two-layered microfluid channel, and method of manufacturing three-dimensional microstructures

ABSTRACT

An optofluidic lithography system including a membrane, a microfluidic channel, and a pneumatic chamber is provided. The membrane may be positioned between a pneumatic chamber and a microfluidic channel. The microfluidic channel may have a height corresponding to a displacement of the membrane and have a fluid flowing therein, the fluid being cured by light irradiated from the bottom to form a microstructure. The pneumatic chamber may induce the displacement of the membrane depending on an internal atmospheric pressure thereof.

The present application is a Continuation Application of co-pending U.S.patent application Ser. No. 12/555,428 (filed on Sep. 8, 2009) under 35U.S.C. §120, which claims priority to Korean Patent Application No.10-2008-0088683 (filed on Sep. 9, 2008) under 35 U.S.C. §119, which areall hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The described technology relates to an optofluidic lithography system, amethod of manufacturing a two-layered microfluidic channel, and a methodof manufacturing three-dimensional microstructures.

BACKGROUND

Fine structures such as microstructures and nanostructures may beapplied to various fields such as photonic materials,micro-electromechanical systems (MEMS), biomaterials, self-assembly andso on. Recently, as a technique for producing such fine structures,continuous-flow lithography has been proposed (D. Dendukuri, D.Pregibon, J. Collins, T. Hatton, P. Doyle. “Continuous-flow lithographyfor high-throughput microparticle synthesis.” Nature materials, vol. 5,pp. 365-369, 2006; U.S. Patent No. 2007-0105972, Microstructuresynthesis by flow lithography and polymerization). The continuous-flowlithography involves flowing a photocurable fluid into a microfluidicchannel, exposing the photocurable fluid to a predetermined shape oflight to selectively cure the photocurable fluid, and continuouslyproducing various kinds of free-floating microstructures. When thecontinuous-flow lithography is used, microstructures having variousshapes, sizes, and chemical compositions can be produced more quicklyand easily.

However, the continuous-flow lithography proposed in the above paper canproduce only single-layered microstructures. Therefore, it is difficultto produce three-dimensional microstructures with a complex structure.Further, the continuous-flow lithography proposed in the above paper,uses a photomask, which is not programmable in real time. Therefore, thecontinuous-flow lithography has a limited time-and-space flexibility inproducing microstructures.

SUMMARY

In one exemplary embodiment, an optofluidic lithography system isprovided. The optofluidic lithography system includes a membrane, amicrofluidic channel, and a pneumatic chamber. The membrane ispositioned between a pneumatic chamber and a microfluidic channel. Themicrofluidic channel has a height corresponding to a displacement of themembrane and a fluid flowing therein. The fluid is cured by lightirradiated from the bottom to form a microstructure. The pneumaticchamber induces the displacement of the membrane depending on aninternal atmospheric pressure thereof.

In another exemplary embodiment, a method of manufacturing a two-layeredmicrofluidic channel is provided. A pneumatic-chamber mold is placed ona wafer, and PDMS is poured into a pneumatic-chamber mold. The wafer andthe pneumatic-chamber mold are removed, and a hole is bored through thePDMS covering the pneumatic-chamber mold such that a tube for injectingor discharging air into or from a pneumatic chamber can be inserted. Theintermediate product having gone through the placing PDMS on thepneumatic-chamber mold is placed on the intermediate product having gonethrough the placing PDMS on the microfluidic-channel mold, and both ofthe PDMS are attached to each other to form a pneumatic chamber. Themicrofluidic-channel mold is removed. A hole is bored through the PDMScovering the microfluidic-channel mold such that a tube for injecting ordischarging a fluid into or from a microfluidic channel can be inserted.The wafer is removed, and a light transmitting substrate is attached tothe bottom to form the microfluidic channel. A fluid is injected intothe microfluidic channel.

In still another exemplary embodiment, a method of manufacturingthree-dimensional microstructures is provided. A fluid is injected intoa microfluidic channel positioned in a lower portion of a two-layeredmicrofluidic channel. Air is injected into or discharged from apneumatic chamber above the microfluidic channel to deform a membraneformed between the microfluidic channel and the pneumatic chamber suchthat the height of the microfluidic channel is adjusted. Light isirradiated into the microfluidic channel to cure the fluid, therebyforming a layer on a substrate.

In still another exemplary embodiment, a method of manufacturingthree-dimensional microstructures is provided. A fluid is injected intoa microfluidic channel positioned in a lower portion of a two-layeredmicrofluidic channel. Air is injected into or discharged from apneumatic chamber positioned above the microfluidic channel to deform amembrane formed between the microfluidic channel and the pneumaticchamber such that the height of the microfluidic channel is adjusted.Light is irradiated into the microfluidic channel to cure the fluid suchthat a layer is formed on a substrate. A cleaning solution is flowedinto the microfluidic channel to wash out the remaining fluid. Aninternal atmospheric pressure of the pneumatic chamber is decreased toincrease the height of the microfluidic channel. Light is irradiatedinto the microfluidic channel to form a new layer on the layer formed onthe substrate, while flowing a different fluid into the microfluidicchannel.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features and advantages of the present disclosurewill become more apparent to those of ordinary skill in the art bydescribing in detail exemplary embodiments thereof with reference to theattached drawings, in which:

FIG. 1 is a diagram for explaining an optofluidic lithography systemaccording to an exemplary embodiment of this disclosure;

FIG. 2 is a diagram for explaining a method of manufacturing atwo-layered microfluidic channel according to an exemplary embodiment ofthis disclosure;

FIGS. 3A to 3C are diagrams for explaining a method of manufacturingthree-dimensional microstructures using the optofluidic lithographysystem according to an exemplary embodiment of this disclosure;

FIG. 4 is a graph showing correlations among the internal atmosphericpressure of a pneumatic chamber, the exposure time of ultraviolet light,and the height of a layer formed in a microfluidic channel; and

FIGS. 5A to 5D are scanning electron microscope (SEM) photographsshowing various three-dimensional structures manufactured by the methodof FIG. 2.

FIGS. 6A and 6B are diagrams for explaining methods of manufacturingthree-dimensional microstructures by injecting different kinds of fluidsinto a two-layered microfluidic channel according to an exemplaryembodiment.

FIG. 7 is a photograph showing three-dimensional structures manufacturedby the method of FIG. 6A or 6B.

FIG. 8 is a photograph showing an array of patterned hydrogels includingdifferent living cells, manufactured by the method of FIG. 6A or 6B.

DETAILED DESCRIPTION

It will be readily understood that the components of the presentdisclosure, as generally described and illustrated in the Figuresherein, could be arranged and designed in a wide variety of differentconfigurations. Thus, the following more detailed description of theexemplary embodiments of an apparatus and method in accordance with thepresent disclosure, as represented in the Figures, is not intended tolimit the scope of the disclosure, as claimed, but is merelyrepresentative of certain examples of embodiments in accordance with thedisclosure. The presently described exemplary embodiments will be bestunderstood by reference to the drawings, wherein like parts aredesignated by like reference numerals throughout. Moreover, the drawingsare not necessarily to scale, and the size and relative sizes of thelayers and regions may have been exaggerated for clarity.

It will also be understood that when an element or layer is referred toas being “on,” another element or layer, the element or layer may bedirectly on the other element or layer or intervening elements or layersmay be present.

FIG. 1 is a diagram for explaining an optofluidic lithography systemaccording to an exemplary embodiment of this disclosure.

Referring to FIG. 1, the optofluidic lithography system includes atwo-layered microfluidic channel 10.

The two-layered microfluidic channel 10 includes a pneumatic chamber 12,a membrane 15, and a microfluidic channel 14. The pneumatic chamber 12is connected to an air injection pump 30 through a tube 31. Through thetube 31, air is injected into the pneumatic chamber 12 from the airinjection pump 30 or discharged from the pneumatic chamber 12. Throughthis process, it is possible to adjust the internal atmospheric pressureof the pneumatic chamber 12. A material surrounding the pneumaticchamber 12 may be polydimethylsiloxane (PDMS).

Under the pneumatic chamber 12, a membrane 15 is provided. The membrane15 is deformed depending on the internal atmospheric pressure of thepneumatic chamber 12. As the internal atmospheric pressure of thepneumatic chamber 12 increases, the membrane 15 is swollen toward themicrofluidic channel 14. On the other hand, as the internal atmosphericpressure of the pneumatic chamber 12 decreases, the membrane 15 isswollen toward the pneumatic chamber 12. The membrane 15 may be formedof PDMS, which has an oxygen-transmitting property. Therefore, it ispossible to prevent a situation in which an oxygen layer is formed onthe surface of the membrane 15 and a photocurable fluid cured by lightadheres to the membrane 15.

Under the membrane 15, the microfluidic channel 14 is provided. Themicrofluidic channel 14 may be connected to a fluid injection tube 18,through which a fluid 11 is injected into the microfluidic channel 14,and a fluid discharge tube 28 through which the fluid 11 is dischargedfrom the microfluidic channel 14, for example. Inside the microfluidicchannel 14, the fluid 11 flows. As the fluid 11, a photocurable fluidmay be used, for example. The photocurable fluid is cured, depending onlight provided to the microfluidic channel, and then output. Morespecifically, while the photocurable fluid is exposed to light insidethe microfluidic channel 14, it is cured to produce microstructures. Theheight of the microfluidic channel 14 is determined by a displacement ofthe membrane 15. When the internal atmospheric pressure of the pneumaticchamber 12 increases so that the membrane 15 is swollen toward themicrofluidic channel 14, the height of the microfluidic channel 14decreases. On the other hand, when the internal atmospheric pressure ofthe pneumatic chamber 12 decreases so that the membrane 15 is swollentoward the pneumatic chamber 12, the height of the microfluidic channel14 increases. A material surrounding the microfluidic channel other thanthe bottom thereof may be PDMS.

Under the microfluidic channel 14, a substrate 20 is provided. Thesubstrate 20 may be a glass substrate, for example. On the substrate 20,the fluid cured through the exposure to light forms a layer. Through thelower surface of the substrate 20, light is irradiated to cure thefluid.

The optofluidic lithography system according to an exemplary embodimentof this disclosure may further include a light source 40, a spatiallight modulator 51, and a demagnification lens 80, in addition to thetwo-layered microfluidic channel 10. Further, the optofluidiclithography system may include a beam splitter 70 and a camera 60 whichare required for monitoring the microfluidic channel 14.

The light source 40 serves to provide light capable of curing aphotocurable fluid 41 flowing in the microfluidic channel 14 to thespatial light splitter 51. The light source 40 may be an ultravioletlight source, for example. Otherwise, the light source 40 may be anX-ray, visible light, or infrared light source depending on the type ofphotocurable fluid. The light source 40 may include an ultraviolet lightsource collimator 42 and a mirror 44. The ultraviolet light sourcecollimator 42 serves to output parallel ultraviolet light. The mirror 44serves to provide the light output from the ultraviolet light sourcecollimator 42 to the spatial light modulator 51.

The spatial light modulator 51 serves to modulate the light providedfrom the light source 40. FIG. 1 illustrates a digital micromirrordevice. The spatial light modulator 51 may be manufactured in atwo-dimensional array or one-dimensional array type. Further, a deviceother than the micromirror, such as a liquid crystal display (LCD), maybe used to manufacture the spatial light modulator 51. In the spatiallight modulator 51, light modulation can be programmed. That is, thespatial light modulator 51 can selectively deliver light that isincident on a desired pixel among pixels included in the spatial lightmodulator 51 to the demagnification lens 80 at a desired time. The lightmodulation of the spatial light modulator 51 may be controlled by acomputer 50, for example. That is, images produced by the computer 50are delivered to the programmable spatial light modulator 51, and thespatial light modulator 51 controls the shape of light provided to themicrofluidic channel 14. The shape of microstructures produced in themicrofluidic channel 14 can be controlled by the programmable spatiallight modulator 51.

The demagnification lens 80 serves to demagnify the modulated lightprovided from the spatial light modulator 51 to provide to themicrofluidic channel 14. As the demagnification lens 80, a microscopeobject lens 10 x may be used to project an image of the spatial lightmodulator 51 onto a final object plane at a demagnification factor ofabout 8.9, for example.

The beam splitter 70 serves to deliver the modulated light provided fromthe spatial light modulator 51 to the microfluidic channel 14 throughthe demagnification lens 80. Further, the beam splitter 70 serves todeliver an image from the microfluidic channel 14 to the camera 60through the demagnification lens 80. The beam splitter 80 may be adichroic mirror as shown in FIG. 1, for example.

The camera 60 outputs an electrical image signal corresponding to theimage of the microfluidic channel 14. The camera 60 may be acharge-coupled device (CCD), for example.

Since the optofluidic lithography system shown in FIG. 1 employs thetwo-layered microfluidic channel capable of adjusting the height of themicrofluidic channel, the scale of the system can be reduced. Further,the number of manufacturing processes and the manufacturing costs ofthree-dimensional microstructures can be reduced. Further, as thespatial light modulator is employed, a mask may not be used. Further,while an existing optofluidic lithography system using a mask canproduce only microstructures with a predetermined shape, the optofluidiclithography system shown in FIG. 1 can produce microstructures havingvarious shapes without the replacement of a mask. Further, theoptofluidic lithography system shown in FIG. 1 makes it possible tocontrol in-situ photopolymerization in real time.

FIG. 2 is a diagram for explaining a method of manufacturing atwo-layered microfluidic channel according to an exemplary embodiment ofthis disclosure.

Referring to operation (i) of FIG. 2, a first mold 110 is placed on awafer 120, and PDMS 100 is poured into the first mold 110. The firstmold 110 is used for forming a pneumatic chamber. The wafer 120 may be asilicon wafer, for example. Referring to operation (ii) of FIG. 2, thewafer 120 and the first mold 110 are removed. To insert a tube throughwhich air can be injected into or discharged from a pneumatic chamber, ahole 130 is bored through the PDMS. Referring to operation (iii) of FIG.2, a second mold 210 is placed on a wafer 220, and PDMS 100 is pouredinto the second mold 210. The second mold 210 is used for forming amicrofluidic channel. Referring to operation (iv) of FIG. 2, theintermediate product having gone through operation (ii) of FIG. 2 isplaced on the intermediate product having gone through operation (iii)of FIG. 2, and both of the PDMS 100 are attached to each other to form apneumatic chamber 140. Before both of the PDMS 100 are attached to eachother, both of the PDMS 100 are surface-treated by oxygen plasma or acorona discharger. Then, both of the PDMS 100 are attached to each otherand sealed by application of heat. Referring to operation (v) of FIG. 2,PDMS is additionally poured onto the PDMS covering the second mold for amicrofluidic channel such that the PDMS becomes thick. When the width W1of the PDMS in operation (i) of FIG. 2 is larger than the width W2 ofthe PDMS in operation (iii) of FIG. 2, operation (v) may be omitted.Referring to operation (vi) of FIG. 2, the second mold 210 is removed.To insert a fluid injection tube and a fluid discharge tube throughwhich a fluid can be injected into and discharged from the microfluidicchannel, holes 230 and 330 are bored through the PDMS. The wafer 220 isremoved, and a light transmitting substrate 320 is attached. Then, amicrofluidic channel 240 is formed, into which a fluid is injected. Thelight transmitting substrate 320 may be a glass substrate, for example.Referring to operation (vii) of FIG. 2, a fluid 300 is injected into themicrofluidic channel 240 through the fluid injection tube. Between thepneumatic chamber and the microfluidic channel, a membrane 200 isprovided. The membrane 200 is deformed, depending on the atmosphericpressure of the pneumatic chamber 140, to determine the height of themicrofluidic channel 240. The thickness of the membrane is about 200 μm.

FIGS. 3A to 3C are diagrams for explaining a method of manufacturingthree-dimensional microstructures using the optofluidic lithographysystem according to an exemplary embodiment of this disclosure.Referring to FIG. 3A (i), air is injected into the pneumatic chamber 12such that the internal atmospheric pressure thereof increases. As theinternal atmospheric pressure of the pneumatic chamber 12 increases, themembrane 15 formed between the pneumatic chamber 12 and the microfluidicchannel 14 is swollen toward the microfluidic channel 14. A distancefrom the lowermost point of the membrane 15 and the bottom of themicrofluidic channel 14 corresponds to the height h of the microfluidicchannel 14. Inside the microfluidic channel 14, a fluid 11 flows. Lightis irradiated through the lower surface of the substrate 20 under themicrofluidic channel 14. The fluid 11 exposed to the light inside themicrofluidic channel 14 is cured to form a first layer on the substrate20. The first layer is grown up to the height h of the microfluidicchannel 14. FIG. 3A (ii) illustrates the first layer 16 of the fluid 11cured through the exposure to light. FIG. 3A (iii) illustrates the shapeof the light irradiated through the lower surface of the substrate 20.The shape of the irradiated light is adjusted so as to correspond to adesired shape of the first layer. The size of the irradiated light isadjusted by the demagnification lens, and the shape of the irradiatedlight is controlled by the spatial light modulator.

Referring to FIG. 3B (i), air is discharged from the pneumatic chamber12 of FIG. 3A such that the internal atmospheric pressure thereofdecreases. The membrane 15 disposed lower position of pneumatic chamber12 ascends toward the pneumatic chamber 12. The height h of themicrofluidic channel 14 increases in comparison with that of FIG. 3A.Then, light is irradiated through the lower surface of the substrate 20under the microfluidic channel 14. The fluid 11 exposed to the lightinside the microfluidic channel 14 is cured to form a second layer onthe first layer. The height of the second layer is obtained bysubtracting the height of the first layer from the height h of themicrofluidic channel 14. FIG. 3B (ii) illustrates the first layer andthe second layer 26 formed on the first layer. FIG. 3B (iii) illustratesthe shape of light irradiated through the lower surface of the substrate20. The shape of the irradiated light is adjusted so as to correspond toa desired shape of the second layer.

Referring to FIG. 3C (i), air is discharged from the pneumatic chamber12 of FIG. 3B such that the internal atmospheric pressure thereofdecreases. Then, the membrane 15 under the pneumatic chamber 12 isswollen toward the pneumatic chamber 12. The height h of themicrofluidic channel 14 corresponds to a distance from the bottom of themicrofluidic channel 14 to the uppermost point of the membrane 15, andincreases in comparison with that of FIG. 3B. Then, light is irradiatedthrough the lower surface of the substrate 20 under the microfluidicchannel 14. The fluid 11 exposed to the light inside the microfluidicchannel 14 is cured to form a third layer on the second layer. Theheight of the third layer is obtained by subtracting the heights of thefirst and second layers from the height h of the microfluidic channel14. FIG. 3C (ii) illustrates the first layer 16, the second layer 26,and the third layer 36 formed on the second layer. FIG. 3C (iii)illustrates the shape of the light irradiated through the lower surfaceof the substrate 20. The shape of the irradiated light is adjusted so asto correspond to a desired shape of the third layer. The exposure timeof the light irradiated to the microfluidic channel through thesubstrate differs depending on the intensity of the light source, butranges from 0.1 to 0.2 seconds.

FIG. 4 is a graph showing the height of a layer formed by the cure ofthe photocurable fluid inside the microfluidic channel, depending on theinternal atmospheric pressure of the pneumatic chamber. Referring toFIG. 4, the height of the layer changes linearly depending on theinternal atmospheric pressure of the pneumatic chamber. Further, theheight of the microfluidic channel may not change because of anidentical internal atmospheric pressure of the pneumatic chamber. Inthis case, when the exposure time of ultraviolet light lengthens,polymerization additionally occurs in an oxygen inhibition layer aroundthe membrane. Therefore, although the internal atmospheric pressure ofthe pneumatic chamber is identical, the height of the layer may increasewhen the exposure time of ultraviolet light lengthens.

FIGS. 5A to 5D are scanning electron microscope (SEM) photographsshowing various three-dimensional structures manufactured by theabove-described method. FIG. 5A shows a microstructure formed in afive-layered pyramid shape. FIG. 5B shows a five-layered minute-wheelstructure. FIG. 5C shows a structure in which posts having variousheights are arranged in a lattice shape. FIG. 5D shows variousmicrostructures which are uniformly arranged in a two-dimensionalmanner. As such, it is possible to manufacture the three-dimensionalmicrostructures having complex shapes through the method ofmanufacturing three-dimensional microstructures according to thisdisclosure. Scale bars on the photographs indicate 50 μM, but a scalebar of FIG. 5D exceptionally indicates 100 μm.

FIGS. 6A and 6B are diagrams for explaining methods of manufacturingthree-dimensional microstructures by injecting different kinds of fluidsinto a two-layered microfluidic channel according to an exemplaryembodiment. Referring to FIG. 6A, while flowing a material A into themicrofluidic channel 14 through the fluid injection tube 18, light 13 isirradiated to cure the material A into a desired shape (operation (i)).The light may be X-ray, ultraviolet light, visible light, or infraredlight, for example. A cleaning solution is flowed into the microfluidicchannel 14 through the fluid injection tube 18 to wash out the remainingmaterial A (operation (ii)). The cleaning solution may be ethanol ordeionized water. While flowing a material B into the microfluidicchannel 14 through the fluid injection tube 18, light 13 is irradiatedonto the material B to cure the material B into a desired shape on thematerial A cured in operation (i) (operation (iii)). The above-describedprocess may be performed in reverse order. Referring to FIG. 6B, atwo-layered microfluidic channel according to an exemplary embodiment ofthis disclosure includes a plurality of fluid injection tubes. Whileflowing a material A into the microfluidic channel 14 through one fluidinjection tube 18A, light 13 is irradiated to cure the material A into adesired shape (operation (i)). The light may be X-ray, ultravioletlight, visible light, or infrared light, for example. A cleaningsolution is flowed into the microfluidic channel 14 through anotherfluid injection tube 18B to wash out the remaining material A (operation(ii)). The cleaning solution may be ethanol or deionized water. Whileflowing a material B into the microfluidic channel 14 through anotherfluid injection tube 18C, light 13 is irradiated onto the material B tocure the material B into a desired shape on the material A cured inoperation (i) (operation (iii)). The above-described process may beperformed in reverse order. As described above, it is possible tomanufacture three-dimensional microstructures composed of differentmaterials using the two-layered microfluidic channel according to thisdisclosure.

FIG. 7 (i) and (ii) are photographs showing three-dimensionalmicrostructures manufactured by the method of FIG. 6A or 6B. Referringto FIG. 7 (i), structures composed of two kinds of materials are stackedin a vertical direction. A small drawing on the lower left-hand side ofFIG. 7 (i) is a perspective view of the structure. Referring to FIG. 7(ii), pyramid-shaped structures are placed at the bottom, and anotherstructure formed of a different material is stacked on thepyramid-shaped structures. As a whole, the structures form a rectangularparallelepiped shape. A small drawing on the lower left-hand side ofFIG. 7 (ii) is a perspective view of the structures. Scale bars in theright bottom side of FIG. 7 (i) and (ii) indicate 100 μm.

FIG. 8 is a photograph showing arrangements of patterned hydrogelsincluding different living cells, manufactured by the method of FIG. 6Aor 6B according to an exemplary embodiment of this disclosure. When themethod of manufacturing three-dimensional microstructures according tothis disclosure is used, it is possible to manufacture microstructuressuch as three-dimensional hydrogel structures of which each portionincludes different living cells. Referring to FIG. 8, different livingcells are dyed with different fluorescent materials. A first layer(orange) is formed in a cross shape, and a second layer (green) isformed in a square shape. A photograph shown on the right is obtained bymagnifying one of the arrangements of the photograph on the left. Ascale bar in the photograph on the left indicates 100 μm. As such, whenthe method of manufacturing three-dimensional microstructures accordingto this disclosure is used, it is possible to manufacture a structure ofwhich each portion is composed of different materials and includesdifferent living cells.

The foregoing is illustrative of the present disclosure and not to beconstrued as limiting thereof. Although numerous embodiments of thepresent disclosure have been described, those skilled in the art willreadily appreciate that many modifications are possible in theembodiments without materially departing from the novel teachings andadvantages of the present disclosure. Accordingly, all suchmodifications are intended to be included within the scope of thepresent disclosure as defined in the claims. Therefore, it is to beunderstood that the foregoing is illustrative of the present disclosurewhich is not to be construed as limited to the specific embodimentsdisclosed, and that modifications to the disclosed embodiments, as wellas other embodiments, are intended to be included within the scope ofthe appended claims. The present disclosure is defined by the followingclaims, with equivalents of the claims to be included therein.

What is claimed is:
 1. An optofluidic lithography system comprising: amembrane; a pneumatic chamber, the pneumatic chamber configured toinduce a displacement of the membrane depending on an internalatmospheric pressure thereof; and a microfluidic channel adjacent to themembrane and outside the pneumatic chamber, the microfluidic channelhaving a height corresponding to the displacement of the membrane andhaving a fluid flowing therein, the fluid being cured by lightirradiated from a bottom of the microfluidic channel to form amicrostructure, wherein the pneumatic chamber is positioned above themicrofluidic channel to displace the membrane forming a bottom surfaceof the pneumatic chamber and a top surface of the microfluidic channelsuch that the height of the microfluidic channel is adjusted by thedisplacement of the membrane, wherein a height of the microstructure isdetermined by the displacement of the membrane.
 2. The optofluidiclithography system according to claim 1, wherein the membrane is formedof polydimethylsiloxane.
 3. The optofluidic lithography system accordingto claim 1, wherein the fluid is photocurable.
 4. The optofluidiclithography system according to claim 1, wherein the pneumatic chamberis connected to an air injection pump capable of introducing air to anddischarging air from the pneumatic chamber.
 5. The optofluidiclithography system according to claim 1 further comprising: an injectiontube through which the fluid is injected into the microfluidic channel;and a discharge tube through which the fluid is discharged from themicrofluidic channel.
 6. The optofluidic lithography system according toclaim 1, further comprising: a light source configured to generate lightcapable of curing the fluid flowing in the microfluidic channel; and aspatial light modulator configured to modulate the light provided fromthe light source.